Handle self-building and use builder domain for envelopes

consensus/state_processing/src/per_block_processing/signature_sets.rs

@@ -372,6 +372,8 @@ where
     E: EthSpec,
     F: Fn(usize) -> Option<Cow<'a, PublicKey>>,
 {
+    let proposer_index = state.latest_block_header().proposer_index;
+    let builder_index = signed_envelope.message.builder_index(proposer_index);
     let domain = spec.get_domain(
         state.current_epoch(),
         Domain::BeaconBuilder,
@@ -379,9 +381,8 @@ where
         state.genesis_validators_root(),
     );
     let message = signed_envelope.message.signing_root(domain);
-    let pubkey = get_pubkey(signed_envelope.message.builder_index as usize).ok_or(
-        Error::ValidatorUnknown(signed_envelope.message.builder_index),
-    )?;
+    let pubkey =
+        get_pubkey(builder_index as usize).ok_or(Error::ValidatorUnknown(builder_index))?;
 
     Ok(SignatureSet::single_pubkey(
         &signed_envelope.signature,
@@ -400,6 +401,7 @@ where
     E: EthSpec,
     F: Fn(usize) -> Option<Cow<'a, PublicKey>>,
 {
+    // TODO(EIP-7732): needs to handle self building!
     let domain = spec.get_domain(
         state.current_epoch(),
         Domain::BeaconBuilder,

consensus/types/src/core/consts.rs

@@ -25,3 +25,6 @@ pub mod bellatrix {
 pub mod deneb {
     pub use kzg::VERSIONED_HASH_VERSION_KZG;
 }
+pub mod gloas {
+    pub const BUILDER_INDEX_SELF_BUILD: u64 = u64::MAX;
+}

consensus/types/src/execution/execution_payload_envelope.rs

@@ -1,3 +1,4 @@
+use crate::consts::gloas::BUILDER_INDEX_SELF_BUILD;
 use crate::test_utils::TestRandom;
 use crate::{
     EthSpec, ExecutionPayloadGloas, ExecutionRequests, ForkName, Hash256, KzgCommitments,
@@ -17,8 +18,10 @@ use tree_hash_derive::TreeHash;
 pub struct ExecutionPayloadEnvelope<E: EthSpec> {
     pub payload: ExecutionPayloadGloas<E>,
     pub execution_requests: ExecutionRequests<E>,
+    // The builder index is private so that callers are forced to handle the case where it equals
+    // BUILDER_INDEX_SELF_BUILD.
     #[serde(with = "serde_utils::quoted_u64")]
-    pub builder_index: u64,
+    builder_index: u64,
     pub beacon_block_root: Hash256,
     pub slot: Slot,
     pub blob_kzg_commitments: KzgCommitments<E>,
@@ -27,6 +30,28 @@ pub struct ExecutionPayloadEnvelope<E: EthSpec> {
 
 impl<E: EthSpec> SignedRoot for ExecutionPayloadEnvelope<E> {}
 
+impl<E: EthSpec> ExecutionPayloadEnvelope<E> {
+    /// Fetch the validator index of the builder of this execution payload.
+    ///
+    /// This falls back to the provided `proposer_index` if the builder index indicates
+    /// self-building.
+    pub fn builder_index(&self, proposer_index: u64) -> u64 {
+        if self.builder_index == BUILDER_INDEX_SELF_BUILD {
+            proposer_index
+        } else {
+            self.builder_index
+        }
+    }
+
+    /// Fetch the raw builder index, which may be `BUILDER_INDEX_SELF_BUILD` to indicate
+    /// self-building.
+    ///
+    /// This method should be used sparingly.
+    pub fn raw_builder_index(&self) -> u64 {
+        self.builder_index
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

consensus/types/src/execution/signed_execution_payload_envelope.rs

@@ -39,12 +39,14 @@ impl<E: EthSpec> SignedExecutionPayloadEnvelope<E> {
     ///
     /// The `parent_state` is the post-state of the beacon block with
     /// block_root = self.message.beacon_block_root
-    /// TODO(EIP-7732): maybe delete this function later
+    /// TODO(EIP-7732): maybe delete this function later (it is inefficient)
     pub fn verify_signature_with_state(
         &self,
         parent_state: &BeaconState<E>,
         spec: &ChainSpec,
     ) -> Result<bool, BeaconStateError> {
+        let proposer_index = parent_state.latest_block_header().proposer_index;
+        let builder_index = self.message.builder_index(proposer_index) as usize;
         let domain = spec.get_domain(
             parent_state.current_epoch(),
             Domain::BeaconBuilder,
@@ -53,23 +55,18 @@ impl<E: EthSpec> SignedExecutionPayloadEnvelope<E> {
         );
         let pubkey = parent_state
             .validators()
-            .get(self.message.builder_index as usize)
+            .get(builder_index)
             .and_then(|v| {
                 let pk: Option<PublicKey> = v.pubkey.decompress().ok();
                 pk
             })
-            .ok_or(BeaconStateError::UnknownValidator(
-                self.message.builder_index as usize,
-            ))?;
+            .ok_or(BeaconStateError::UnknownValidator(builder_index))?;
         let message = self.message.signing_root(domain);
 
         Ok(self.signature.verify(&pubkey, message))
     }
 
     /// Verify `self.signature`.
-    ///
-    /// If the root of `block.message` is already known it can be passed in via `object_root_opt`.
-    /// Otherwise, it will be computed locally.
     pub fn verify_signature(
         &self,
         pubkey: &PublicKey,
@@ -77,9 +74,11 @@ impl<E: EthSpec> SignedExecutionPayloadEnvelope<E> {
         genesis_validators_root: Hash256,
         spec: &ChainSpec,
     ) -> bool {
+        // Signed envelopes using the new BeaconBuilder domain per the spec:
+        // https://github.com/ethereum/consensus-specs/blob/v1.7.0-alpha.1/specs/gloas/beacon-chain.md#new-verify_execution_payload_envelope_signature
         let domain = spec.get_domain(
             self.epoch(),
-            Domain::BeaconProposer,
+            Domain::BeaconBuilder,
             fork,
             genesis_validators_root,
         );